Comparison of characteristics and outcomes for type A aortic dissection surgery by Māori, Pasifika or other ethnicities
View Article PDF
Ethnic disparities is a leading problem in healthcare, affecting many cardiovascular conditions and mortality rates in New Zealand.1,2 Type A aortic dissection has high fatality from associated cardiac tamponade, malperfusion of critical organ(s), aortic regurgitation and vessel rupture.3,4 Emergency surgery is generally recommended due to the high risk of death if left untreated, 1–3%/hour in the first 24 hours reaching hospital, 30% at one week and 90% at one month; however, operative mortality remains high at 17–25% in contemporary literature.3,5 Key risk factors include hypertension and aortopathy syndromes; however, possible ethnic associations and differences in presentation and outcomes are less well established.3,4 We reviewed our type A aortic dissection surgery experience by ethnicity.
Methods
Consecutive type A aortic dissection surgeries performed at Auckland City Hospital during March 2003–March 2017 were divided into three ethnic groups—Māori, Pasifika and Other. Ethnicity was obtained from clinical records, whereby patients reported their self-identified one or more ethnic groups they belonged to, and when selected Māori ethnicity was prioritised above Pasifika, and both above others in its coding. Data were extracted from the prospectively collected cardiothoracic surgical unit database. Critical pre-operative state was defined as having inotropic support, cardiogenic shock, mechanical ventilation and/or cardiopulmonary resuscitation. Malperfusion syndrome were defined as the presence of coronary, limb, brain and/or abdominal viscera ischaemia of new onset related to the aortic dissection, using clinical, biomarker and radiological tests. Creatinine clearance was calculated using the Cockcroft-Gault formula. The EuroSCORE and EuroSCORE II were retrospectively calculated.7,8 The Society of Thoracic Surgeon’s (STS) definitions was used for all outcomes including operative mortality (in-hospital or within 30 days) and post-operative complications.9 Total mortality during follow-up from operation date until 31 January 2019 was checked against the National Mortality Database, and late mortality defined by all deaths that occurred after the operative mortality defined period.
Quantitative and categorical variables were described using mean+/-standard deviation and frequency (percentage) respectively. Univariable analysis was performed using Analysis of Variance (ANOVA) and Chi-squared tests respectively. Survival was presented using Kaplan-Meier plots and compared by the log-rank test. Age-standardisation to calculate standardised mortality ratio (SMR) for operative and late mortality for Māori and Pasifika patients compared to other ethnicities was performed using the 2013 New Zealand Census District Health Board and ethnic group-based population age structures. Stepwise logistic regression and Cox Proportional Hazards regression were the multivariable analysis techniques used for cross-sectional and longitudinal outcomes. The significance level was set at P-value less than 0.05 and all tests were two-tailed.
Results
Among 327 aortic dissection surgery patients, the ethnic breakdown was Māori 45 (14%), Pasifika 91 (28%) and other 191 (58%). Table 1 lists the characteristics of the cohort. Māori and Pasifika patients were significantly younger, had higher body mass index and higher prevalence of hypertension, but lower EuroSCORE, EuroSCORE II and presentation with critical pre-operative state than other patients. Māori patients also had a higher prevalence of smoking and family history of aortic dissection than other patients.
Table 1: Cohort characteristics and outcomes.
Operative variables and outcomes are shown in Table 2. There was no statistically significant difference in operative mortality by ethnicity (11–22%), or post-operative complications (composite 62–70%). Figure 1 shows the survival curves by ethnicity with a mean follow-up of 4.3+/-3.3 years, where 1, 5 and 10-year survival were 86, 74 and 54% for Māori; 79, 76 and 72% for Pasifika; and 74, 66 and 54% for Other ethnicities (log-rank P=0.185). The SMR (95% confidence intervals) for operative mortality were 1.18 (0.43–2.62) for Māori and 6.00 (3.67–9.30) for Pasifika; and for late mortality 5.71 (2.90–10.2) and 1.95 (0.72–4.33) respectively.
Table 2: Operative variables and outcomes.
Figure 1: Kaplan-Meier survival curve of the cohort by ethnicity (log-rank p-value P=0.19).
Multivariable analysis are shown in Table 3. Critical pre-operative state, malperfusion syndrome and cross-clamp time were independent predictors of both operative mortality and composite morbidity, while Māori ethnicity and history of myocardial infarction were independently associated with higher late mortality.
Table 3: Multivariable analysis.
Discussion
Unlike other types of cardiovascular disease, few studies have assessed the relationship between type A aortic dissection and ethnicity,10,11 including one other study from New Zealand.12 Pasifika ethnicity is over-represented at 28% in our cohort compared to just 7% in the New Zealand 2018 Census ethnicity breakdown, and non-Māori or Pasifika ethnicities were under-represented (58% versus 80%).13 Māori was previously reported to have significantly higher prevalence of aortic dissection than non-Māori,12 though in our study it was the same as the 14% from the latest Census.12 Non-white and African-American ethnic groups have also been found to have higher prevalence of aortic dissection than their counterparts.10,11 Reviewing the clinical characteristics of aortic dissection patients may provide insight into the ethnic discrepancies of this condition.
Māori and Pasifika patients were significantly younger, which may highlight both their underlying susceptibility for aortic dissection and worse control of cardiovascular risk factors. They had a higher prevalence of hypertension and smoking, both of which are associated with aortic pathologies.3,4,12 Māori in particular had family history of aortic dissection in 11%, more so than other ethnicities as a known risk factor for dissection. These findings are consistent with studies of aortic dissection,10,11 and other cardiovascular diseases, and targeting them for prevention is critical for this condition.1,2 Partly because they are younger, Māori and Pasifika patients appear to tolerate aortic dissection better with lower proportion presenting in critical pre-operative state. In a previous study of coronary artery bypass grafting surgery, characteristics and outcomes from our institution also found Māori to be younger, with higher body mass index, prevalence of diabetes, smoking, heart failure and dialysis, suggesting similarly a greater burden of cardiovascular disease at younger age.14
There were no differences in all in-hospital surgical outcomes by ethnicity, similarly observed in other studies.10,11 Their risk profiles need to be taken into context, however, with Māori and Pasifika patients being younger and having lower proportion with critical pre-operative state, both established adverse prognosticators in cardiac surgery, and lower EuroSCOREs.7–9 After age-standardisation, Pasifika patients had markedly higher operative mortality than other ethnic groups. Although Māori patients did not display this, they were also associated with higher operative and medium-term mortality as well as composite morbidity in a previous local study for coronary artery bypass grafting surgery.14 Greater attention needs to be directed to the peri-operative management of both ethnicities recommended by guidelines such as replacing the aortic valve, root and repairing supra-aortic branches, descending aorta and other visceral vessels if the dissection involve or compromises those areas, and blood pressure control.4 Female sex was previously found to have a strong association with operative mortality of aortic dissection for all New Zealand ethnicities,12 but this was not found in our study.
After aortic dissection surgeries, most deaths and complications occur during the index hospitalisation, but once patients get through this early phase, long-term prognosis is generally favourable.3–5 It is concerning nevertheless that Māori patients had higher age-standardised late mortality, and remained independently associated with higher late mortality in multivariable analysis, and this trend had also previously been seen.12 Their higher prevalence of family history of aortic dissection, and numerically but not statistically more patients with bicuspid aortic valve may contribute to further aortic events. Control of risk factors like hypertension and clinical and close imaging surveillance are the key guideline recommendations long-term after aortic dissection, and the worse outcomes for Māori may be related to impaired implementation.4,15 Strategies including education, strict risk factor control and attendance to follow-up are critical for these patients with the potential to improve their outcomes. For imaging surveillance after aortic dissection surgery, the European Society of Cardiology guidelines recommend aortic imaging at 1 month, 6 month, 12 months, and if stable then this can be spaced out but remain regular.4 Computed tomography (CT) is preferred with magnetic resonance imaging (MRI) as an alternative. The joint guidelines of American Society of Echocardiography and European Society of Cardiovascular imaging recommend aortic imaging at 1, 3, 6 and 12 months followed by yearly examination, again with either CT or MRI.15
This study had some limitations. It is a single-centre observational study. The study had modest power with regards to limited numbers of particularly Māori and Pasifika patients. We did not investigate non-type A aortic dissection or those managed conservatively with medical therapy and/or endovascular treatments. The aetiology of dissection wasn’t routinely investigated so the presence of associated conditions such as Marfan syndrome are unknown. Other characteristics we didn’t collect include time from presentation to surgery, frailty, blood pressure control and medications, cause of death, peri-operative myocardial infarction, cardiovascular readmissions and recurrence of dissection and/or repeat operation. We also were unable to perform age-standardisation analysis, which may have better presented any differences in outcomes by ethnicity given baseline differences in age.
In conclusion, Pasifika patients were over-represented, Māori patients similarly represented and non-Māori or non-Pasifika ethnicities under-represented in our aortic dissection surgery cohort compared to the general population. Māori and Pasifika patients were significantly younger and presented less unwell, but had higher prevalence of cardiovascular risk factors. Importantly, Pasifika and Māori patients had significantly higher age-standardised operative and late mortality respectively. Education, strict risk factor control and surveillance are critical in primary and secondary prevention of aortic dissection, especially ethnicities at high risk.
Summary
Abstract
Aortic dissection is a life-threatening condition frequently requiring emergency surgery. Key risk factors include hypertension and aortopathy syndromes; however, possible ethnic associations and differences in presentation and outcomes are less well established. We compared characteristics and outcomes of type A aortic dissection surgery by ethnicity.
Aim
Method
Consecutive patients having type A aortic dissection surgery at Auckland City Hospital March 2003–March 2017 were divided into three ethnic groups: Māori, Pasifika and ‘other’, and analysed for characteristics, presentation and outcomes.
Results
Among 327 patients, 45 (14%) were Māori, 91 (28%) were Pasifika Islander and 191 (58%) were other ethnicities. Mean age was lowest for Māori 51+/-12 years, then Pasifika 56+/-12 and other ethnicities 63+/-13 (P<0.001). Māori and Pasifika ethnicities had higher body mass index, more hypertension, dyslipidaemia and smoking, but lower proportion presenting in critical pre-operative state. Operative mortality occurred in 5 (11%), 18 (20%) and 42 (22%) for Māori, Pasifika and other ethnicities (P=0.258). Pasifika had higher age-standardised operative mortality standardised mortality ratio 6.00, 95% confidence interval 3.67–9.30 than ‘other’ ethnicities, while Māori had higher age-standardised late mortality 5.71, 2.90–10.2 respectively, and the latter association persisted in multivariable analysis. Critical pre-operative state and malperfusion syndrome independently predicted operative mortality.
Conclusion
Māori and Pasifika patients were younger and present less unwell with type A aortic dissection, but had higher prevalence of cardiovascular risk factors. They had higher age-standardised late and operative mortality respectively, suggesting that aggressive management and risk factor control are critical for these patients.
Author Information
Acknowledgements
Correspondence
Correspondence Email
Competing Interests
1. Disney G, Teng A, Atkinson J, Wilson N, Blakely T. Changing ethnic inequalities in mortality in New Zealand over 30 years: linked cohort studies with 68.9 million person-years of follow-up. Popul Health Metr 2017; 15:15.
2. Grey C, Jackson R, Wells S, Wu B, Poppe K, Harwood M, Sundborn G, Kerr AJ. Trends in ischaemic heart disease: patterns of hospitalisation and mortality rates differ by ethnicity (ANZACS-QI 21). N Z Med J 2018; 131(1478):21–31.
3. Evangelista A, Isselbacher EM, Bossone E, Gleason TG, Eusanio MD, Sechtem U, Ehrlich MP, Trimarchi S, Braverman AC, Myrmel T, Harris KM, Hutchinson S, O'Gara P, Suzuki T, Nienaber CA, Eagle KA; IRAD Investigators. Insights from the International Registry of Acute Aortic Dissection: A 20-Year Experience of Collaborative Clinical Research. Circulation 2018; 137(17):1846–1860.
4. Erbel R, Aboyans V, Boileau C, Bossone E, Bartolomeo RD, Eggebrecht H, Evangelista A, Falk V, Frank H, Gaemperli O, Grabenwöger M, Haverich A, Iung B, Manolis AJ, Meijboom F, Nienaber CA, Roffi M, Rousseau H, Sechtem U, Sirnes PA, Allmen RS, Vrints CJ; ESC Committee for Practice Guidelines. 2014 ESC Guidelines on the diagnosis and treatment of aortic diseases: Document covering acute and chronic aortic diseases of the thoracic and abdominal aorta of the adult. The Task Force for the Diagnosis and Treatment of Aortic Diseases of the European Society of Cardiology (ESC). Eur Heart J. 2014; 35(41):2873–926.
5. Lee TC, Kon Z, Cheema FH, Grau-Sepulveda MV, Englum B, Kim S, Chaudhuri PS, Thourani VH Ailawadi G, Hughes GC, Williams ML, Brennan JM, Svensson L, Gammie JS. Contemporary management and outcomes of acute type A aortic dissection: An analysis of the STS adult cardiac surgery database. J Card Surg 2018; 33(1):7–18.
6. Cockcroft DW, Gault MH. Prediction of Creatinine Clearance from Serum Creatinine. Nephron 1976; 16:31–41.
7. Roques F, Michel P, Goldstone AR, Nashef SA. The logistic EuroSCORE. Eur Heart J. 2003; 24:881–2.
8. Nashef SA, Roques F, Sharples LD, Nilsson J, Smith C, Goldstone AR, Lockowandt U. EuroSCORE II. Eur J Cardiothorac Surg 2012; 41:734–44.
9. O'Brien SM, Feng L, He X, Xian Y, Jacobs JP, Badhwar V, Kurlansky PA, Furnary AP, Cleveland JC Jr, Lobdell KW, Vassileva C, Wyler von Ballmoos MC, Thourani VH, Rankin JS, Edgerton JR, D'Agostino RS, Desai ND, Edwards FH, Shahian DM. The Society of Thoracic Surgeons 2018 Adult Cardiac Surgery Risk Models: Part 2-Statistical Methods and Results. Ann Thorac Surg. 2018; 105(5):1419–1428.
10. Harris D, Klyushnenkova E, Kalsi R, Garrido D, Bhardwaj A, Rabin J, Toursavadkohi S, Diaz J, Crawford R. Non-White Race is an Independent Risk Factor for Hospitalization for Aortic Dissection. Ethn Dis 2016; 26(3):363–8.
11. Bossone E, Pyeritz RE, O'Gara P, Harris KM, Braverman AC, Pape L, Russo MJ, Hughes GC, Tsai TT, Montgomery DG, Nienaber CA, Isselbacher EM, Eagle KA; International Registry of Acute Aortic Dissection (IRAD) Investigators. Acute aortic dissection in blacks: insights from the International Registry of Acute Aortic Dissection. Am J Med 2013; 126(10):909–15.
12. Gupta A, Subramaniam P, Subramaniam P, Hulme K. The sharp end of cardiovascular disease in New Zealand: A review of acute type A aortic dissections of the Waikato. N Z Med J 2015; 128(1419):22–8.
13. Statistics New Zealand [Internet]. Wellington: 2018 Census population and dwelling counts". [Cited 2019 October 4] Available from: http://www.stats.govt.nz/assets/Uploads/2018-Census-population-and-dwelling-counts/Download-data/2018-census-population-and-dwelling-counts.xlsx
14. Wang TK, Ramanathan T, Stewart R, Crengle S, Gamble G, White H. Māori have worse outcomes after coronary artery bypass grafting than Europeans in New Zealand. N Z Med J. 2013; 126(1379):12–22.
15. Goldstein SA, Evangelista A, Abbara S, Arai A, Asch FM, Badano LP, Bolen MA, Connolly HM, Cuéllar-Calàbria H, Czerny M, Devereux RB, Erbel RA, Fattori R, Isselbacher EM, Lindsay JM, McCulloch M, Michelena HI, Nienaber CA, Oh JK, Pepi M, Taylor AJ, Weinsaft JW, Zamorano JL, Dietz H, Eagle K, Elefteriades J, Jondeau G, Rousseau H, Schepens M. J Am Soc Echocardiogr. Multimodality imaging of diseases of the thoracic aorta in adults: from the American Society of Echocardiography and the European Association of Cardiovascular Imaging: endorsed by the Society of Cardiovascular Computed Tomography and Society for Cardiovascular Magnetic Resonance 2015; 28(2):119–82.
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Comparison of characteristics and outcomes for type A aortic dissection surgery by Māori, Pasifika or other ethnicities
View Article PDF
Ethnic disparities is a leading problem in healthcare, affecting many cardiovascular conditions and mortality rates in New Zealand.1,2 Type A aortic dissection has high fatality from associated cardiac tamponade, malperfusion of critical organ(s), aortic regurgitation and vessel rupture.3,4 Emergency surgery is generally recommended due to the high risk of death if left untreated, 1–3%/hour in the first 24 hours reaching hospital, 30% at one week and 90% at one month; however, operative mortality remains high at 17–25% in contemporary literature.3,5 Key risk factors include hypertension and aortopathy syndromes; however, possible ethnic associations and differences in presentation and outcomes are less well established.3,4 We reviewed our type A aortic dissection surgery experience by ethnicity.
Methods
Consecutive type A aortic dissection surgeries performed at Auckland City Hospital during March 2003–March 2017 were divided into three ethnic groups—Māori, Pasifika and Other. Ethnicity was obtained from clinical records, whereby patients reported their self-identified one or more ethnic groups they belonged to, and when selected Māori ethnicity was prioritised above Pasifika, and both above others in its coding. Data were extracted from the prospectively collected cardiothoracic surgical unit database. Critical pre-operative state was defined as having inotropic support, cardiogenic shock, mechanical ventilation and/or cardiopulmonary resuscitation. Malperfusion syndrome were defined as the presence of coronary, limb, brain and/or abdominal viscera ischaemia of new onset related to the aortic dissection, using clinical, biomarker and radiological tests. Creatinine clearance was calculated using the Cockcroft-Gault formula. The EuroSCORE and EuroSCORE II were retrospectively calculated.7,8 The Society of Thoracic Surgeon’s (STS) definitions was used for all outcomes including operative mortality (in-hospital or within 30 days) and post-operative complications.9 Total mortality during follow-up from operation date until 31 January 2019 was checked against the National Mortality Database, and late mortality defined by all deaths that occurred after the operative mortality defined period.
Quantitative and categorical variables were described using mean+/-standard deviation and frequency (percentage) respectively. Univariable analysis was performed using Analysis of Variance (ANOVA) and Chi-squared tests respectively. Survival was presented using Kaplan-Meier plots and compared by the log-rank test. Age-standardisation to calculate standardised mortality ratio (SMR) for operative and late mortality for Māori and Pasifika patients compared to other ethnicities was performed using the 2013 New Zealand Census District Health Board and ethnic group-based population age structures. Stepwise logistic regression and Cox Proportional Hazards regression were the multivariable analysis techniques used for cross-sectional and longitudinal outcomes. The significance level was set at P-value less than 0.05 and all tests were two-tailed.
Results
Among 327 aortic dissection surgery patients, the ethnic breakdown was Māori 45 (14%), Pasifika 91 (28%) and other 191 (58%). Table 1 lists the characteristics of the cohort. Māori and Pasifika patients were significantly younger, had higher body mass index and higher prevalence of hypertension, but lower EuroSCORE, EuroSCORE II and presentation with critical pre-operative state than other patients. Māori patients also had a higher prevalence of smoking and family history of aortic dissection than other patients.
Table 1: Cohort characteristics and outcomes.
Operative variables and outcomes are shown in Table 2. There was no statistically significant difference in operative mortality by ethnicity (11–22%), or post-operative complications (composite 62–70%). Figure 1 shows the survival curves by ethnicity with a mean follow-up of 4.3+/-3.3 years, where 1, 5 and 10-year survival were 86, 74 and 54% for Māori; 79, 76 and 72% for Pasifika; and 74, 66 and 54% for Other ethnicities (log-rank P=0.185). The SMR (95% confidence intervals) for operative mortality were 1.18 (0.43–2.62) for Māori and 6.00 (3.67–9.30) for Pasifika; and for late mortality 5.71 (2.90–10.2) and 1.95 (0.72–4.33) respectively.
Table 2: Operative variables and outcomes.
Figure 1: Kaplan-Meier survival curve of the cohort by ethnicity (log-rank p-value P=0.19).
Multivariable analysis are shown in Table 3. Critical pre-operative state, malperfusion syndrome and cross-clamp time were independent predictors of both operative mortality and composite morbidity, while Māori ethnicity and history of myocardial infarction were independently associated with higher late mortality.
Table 3: Multivariable analysis.
Discussion
Unlike other types of cardiovascular disease, few studies have assessed the relationship between type A aortic dissection and ethnicity,10,11 including one other study from New Zealand.12 Pasifika ethnicity is over-represented at 28% in our cohort compared to just 7% in the New Zealand 2018 Census ethnicity breakdown, and non-Māori or Pasifika ethnicities were under-represented (58% versus 80%).13 Māori was previously reported to have significantly higher prevalence of aortic dissection than non-Māori,12 though in our study it was the same as the 14% from the latest Census.12 Non-white and African-American ethnic groups have also been found to have higher prevalence of aortic dissection than their counterparts.10,11 Reviewing the clinical characteristics of aortic dissection patients may provide insight into the ethnic discrepancies of this condition.
Māori and Pasifika patients were significantly younger, which may highlight both their underlying susceptibility for aortic dissection and worse control of cardiovascular risk factors. They had a higher prevalence of hypertension and smoking, both of which are associated with aortic pathologies.3,4,12 Māori in particular had family history of aortic dissection in 11%, more so than other ethnicities as a known risk factor for dissection. These findings are consistent with studies of aortic dissection,10,11 and other cardiovascular diseases, and targeting them for prevention is critical for this condition.1,2 Partly because they are younger, Māori and Pasifika patients appear to tolerate aortic dissection better with lower proportion presenting in critical pre-operative state. In a previous study of coronary artery bypass grafting surgery, characteristics and outcomes from our institution also found Māori to be younger, with higher body mass index, prevalence of diabetes, smoking, heart failure and dialysis, suggesting similarly a greater burden of cardiovascular disease at younger age.14
There were no differences in all in-hospital surgical outcomes by ethnicity, similarly observed in other studies.10,11 Their risk profiles need to be taken into context, however, with Māori and Pasifika patients being younger and having lower proportion with critical pre-operative state, both established adverse prognosticators in cardiac surgery, and lower EuroSCOREs.7–9 After age-standardisation, Pasifika patients had markedly higher operative mortality than other ethnic groups. Although Māori patients did not display this, they were also associated with higher operative and medium-term mortality as well as composite morbidity in a previous local study for coronary artery bypass grafting surgery.14 Greater attention needs to be directed to the peri-operative management of both ethnicities recommended by guidelines such as replacing the aortic valve, root and repairing supra-aortic branches, descending aorta and other visceral vessels if the dissection involve or compromises those areas, and blood pressure control.4 Female sex was previously found to have a strong association with operative mortality of aortic dissection for all New Zealand ethnicities,12 but this was not found in our study.
After aortic dissection surgeries, most deaths and complications occur during the index hospitalisation, but once patients get through this early phase, long-term prognosis is generally favourable.3–5 It is concerning nevertheless that Māori patients had higher age-standardised late mortality, and remained independently associated with higher late mortality in multivariable analysis, and this trend had also previously been seen.12 Their higher prevalence of family history of aortic dissection, and numerically but not statistically more patients with bicuspid aortic valve may contribute to further aortic events. Control of risk factors like hypertension and clinical and close imaging surveillance are the key guideline recommendations long-term after aortic dissection, and the worse outcomes for Māori may be related to impaired implementation.4,15 Strategies including education, strict risk factor control and attendance to follow-up are critical for these patients with the potential to improve their outcomes. For imaging surveillance after aortic dissection surgery, the European Society of Cardiology guidelines recommend aortic imaging at 1 month, 6 month, 12 months, and if stable then this can be spaced out but remain regular.4 Computed tomography (CT) is preferred with magnetic resonance imaging (MRI) as an alternative. The joint guidelines of American Society of Echocardiography and European Society of Cardiovascular imaging recommend aortic imaging at 1, 3, 6 and 12 months followed by yearly examination, again with either CT or MRI.15
This study had some limitations. It is a single-centre observational study. The study had modest power with regards to limited numbers of particularly Māori and Pasifika patients. We did not investigate non-type A aortic dissection or those managed conservatively with medical therapy and/or endovascular treatments. The aetiology of dissection wasn’t routinely investigated so the presence of associated conditions such as Marfan syndrome are unknown. Other characteristics we didn’t collect include time from presentation to surgery, frailty, blood pressure control and medications, cause of death, peri-operative myocardial infarction, cardiovascular readmissions and recurrence of dissection and/or repeat operation. We also were unable to perform age-standardisation analysis, which may have better presented any differences in outcomes by ethnicity given baseline differences in age.
In conclusion, Pasifika patients were over-represented, Māori patients similarly represented and non-Māori or non-Pasifika ethnicities under-represented in our aortic dissection surgery cohort compared to the general population. Māori and Pasifika patients were significantly younger and presented less unwell, but had higher prevalence of cardiovascular risk factors. Importantly, Pasifika and Māori patients had significantly higher age-standardised operative and late mortality respectively. Education, strict risk factor control and surveillance are critical in primary and secondary prevention of aortic dissection, especially ethnicities at high risk.
Summary
Abstract
Aortic dissection is a life-threatening condition frequently requiring emergency surgery. Key risk factors include hypertension and aortopathy syndromes; however, possible ethnic associations and differences in presentation and outcomes are less well established. We compared characteristics and outcomes of type A aortic dissection surgery by ethnicity.
Aim
Method
Consecutive patients having type A aortic dissection surgery at Auckland City Hospital March 2003–March 2017 were divided into three ethnic groups: Māori, Pasifika and ‘other’, and analysed for characteristics, presentation and outcomes.
Results
Among 327 patients, 45 (14%) were Māori, 91 (28%) were Pasifika Islander and 191 (58%) were other ethnicities. Mean age was lowest for Māori 51+/-12 years, then Pasifika 56+/-12 and other ethnicities 63+/-13 (P<0.001). Māori and Pasifika ethnicities had higher body mass index, more hypertension, dyslipidaemia and smoking, but lower proportion presenting in critical pre-operative state. Operative mortality occurred in 5 (11%), 18 (20%) and 42 (22%) for Māori, Pasifika and other ethnicities (P=0.258). Pasifika had higher age-standardised operative mortality standardised mortality ratio 6.00, 95% confidence interval 3.67–9.30 than ‘other’ ethnicities, while Māori had higher age-standardised late mortality 5.71, 2.90–10.2 respectively, and the latter association persisted in multivariable analysis. Critical pre-operative state and malperfusion syndrome independently predicted operative mortality.
Conclusion
Māori and Pasifika patients were younger and present less unwell with type A aortic dissection, but had higher prevalence of cardiovascular risk factors. They had higher age-standardised late and operative mortality respectively, suggesting that aggressive management and risk factor control are critical for these patients.
Author Information
Acknowledgements
Correspondence
Correspondence Email
Competing Interests
1. Disney G, Teng A, Atkinson J, Wilson N, Blakely T. Changing ethnic inequalities in mortality in New Zealand over 30 years: linked cohort studies with 68.9 million person-years of follow-up. Popul Health Metr 2017; 15:15.
2. Grey C, Jackson R, Wells S, Wu B, Poppe K, Harwood M, Sundborn G, Kerr AJ. Trends in ischaemic heart disease: patterns of hospitalisation and mortality rates differ by ethnicity (ANZACS-QI 21). N Z Med J 2018; 131(1478):21–31.
3. Evangelista A, Isselbacher EM, Bossone E, Gleason TG, Eusanio MD, Sechtem U, Ehrlich MP, Trimarchi S, Braverman AC, Myrmel T, Harris KM, Hutchinson S, O'Gara P, Suzuki T, Nienaber CA, Eagle KA; IRAD Investigators. Insights from the International Registry of Acute Aortic Dissection: A 20-Year Experience of Collaborative Clinical Research. Circulation 2018; 137(17):1846–1860.
4. Erbel R, Aboyans V, Boileau C, Bossone E, Bartolomeo RD, Eggebrecht H, Evangelista A, Falk V, Frank H, Gaemperli O, Grabenwöger M, Haverich A, Iung B, Manolis AJ, Meijboom F, Nienaber CA, Roffi M, Rousseau H, Sechtem U, Sirnes PA, Allmen RS, Vrints CJ; ESC Committee for Practice Guidelines. 2014 ESC Guidelines on the diagnosis and treatment of aortic diseases: Document covering acute and chronic aortic diseases of the thoracic and abdominal aorta of the adult. The Task Force for the Diagnosis and Treatment of Aortic Diseases of the European Society of Cardiology (ESC). Eur Heart J. 2014; 35(41):2873–926.
5. Lee TC, Kon Z, Cheema FH, Grau-Sepulveda MV, Englum B, Kim S, Chaudhuri PS, Thourani VH Ailawadi G, Hughes GC, Williams ML, Brennan JM, Svensson L, Gammie JS. Contemporary management and outcomes of acute type A aortic dissection: An analysis of the STS adult cardiac surgery database. J Card Surg 2018; 33(1):7–18.
6. Cockcroft DW, Gault MH. Prediction of Creatinine Clearance from Serum Creatinine. Nephron 1976; 16:31–41.
7. Roques F, Michel P, Goldstone AR, Nashef SA. The logistic EuroSCORE. Eur Heart J. 2003; 24:881–2.
8. Nashef SA, Roques F, Sharples LD, Nilsson J, Smith C, Goldstone AR, Lockowandt U. EuroSCORE II. Eur J Cardiothorac Surg 2012; 41:734–44.
9. O'Brien SM, Feng L, He X, Xian Y, Jacobs JP, Badhwar V, Kurlansky PA, Furnary AP, Cleveland JC Jr, Lobdell KW, Vassileva C, Wyler von Ballmoos MC, Thourani VH, Rankin JS, Edgerton JR, D'Agostino RS, Desai ND, Edwards FH, Shahian DM. The Society of Thoracic Surgeons 2018 Adult Cardiac Surgery Risk Models: Part 2-Statistical Methods and Results. Ann Thorac Surg. 2018; 105(5):1419–1428.
10. Harris D, Klyushnenkova E, Kalsi R, Garrido D, Bhardwaj A, Rabin J, Toursavadkohi S, Diaz J, Crawford R. Non-White Race is an Independent Risk Factor for Hospitalization for Aortic Dissection. Ethn Dis 2016; 26(3):363–8.
11. Bossone E, Pyeritz RE, O'Gara P, Harris KM, Braverman AC, Pape L, Russo MJ, Hughes GC, Tsai TT, Montgomery DG, Nienaber CA, Isselbacher EM, Eagle KA; International Registry of Acute Aortic Dissection (IRAD) Investigators. Acute aortic dissection in blacks: insights from the International Registry of Acute Aortic Dissection. Am J Med 2013; 126(10):909–15.
12. Gupta A, Subramaniam P, Subramaniam P, Hulme K. The sharp end of cardiovascular disease in New Zealand: A review of acute type A aortic dissections of the Waikato. N Z Med J 2015; 128(1419):22–8.
13. Statistics New Zealand [Internet]. Wellington: 2018 Census population and dwelling counts". [Cited 2019 October 4] Available from: http://www.stats.govt.nz/assets/Uploads/2018-Census-population-and-dwelling-counts/Download-data/2018-census-population-and-dwelling-counts.xlsx
14. Wang TK, Ramanathan T, Stewart R, Crengle S, Gamble G, White H. Māori have worse outcomes after coronary artery bypass grafting than Europeans in New Zealand. N Z Med J. 2013; 126(1379):12–22.
15. Goldstein SA, Evangelista A, Abbara S, Arai A, Asch FM, Badano LP, Bolen MA, Connolly HM, Cuéllar-Calàbria H, Czerny M, Devereux RB, Erbel RA, Fattori R, Isselbacher EM, Lindsay JM, McCulloch M, Michelena HI, Nienaber CA, Oh JK, Pepi M, Taylor AJ, Weinsaft JW, Zamorano JL, Dietz H, Eagle K, Elefteriades J, Jondeau G, Rousseau H, Schepens M. J Am Soc Echocardiogr. Multimodality imaging of diseases of the thoracic aorta in adults: from the American Society of Echocardiography and the European Association of Cardiovascular Imaging: endorsed by the Society of Cardiovascular Computed Tomography and Society for Cardiovascular Magnetic Resonance 2015; 28(2):119–82.
For the PDF of this article,
contact nzmj@nzma.org.nz
Comparison of characteristics and outcomes for type A aortic dissection surgery by Māori, Pasifika or other ethnicities
View Article PDF
Ethnic disparities is a leading problem in healthcare, affecting many cardiovascular conditions and mortality rates in New Zealand.1,2 Type A aortic dissection has high fatality from associated cardiac tamponade, malperfusion of critical organ(s), aortic regurgitation and vessel rupture.3,4 Emergency surgery is generally recommended due to the high risk of death if left untreated, 1–3%/hour in the first 24 hours reaching hospital, 30% at one week and 90% at one month; however, operative mortality remains high at 17–25% in contemporary literature.3,5 Key risk factors include hypertension and aortopathy syndromes; however, possible ethnic associations and differences in presentation and outcomes are less well established.3,4 We reviewed our type A aortic dissection surgery experience by ethnicity.
Methods
Consecutive type A aortic dissection surgeries performed at Auckland City Hospital during March 2003–March 2017 were divided into three ethnic groups—Māori, Pasifika and Other. Ethnicity was obtained from clinical records, whereby patients reported their self-identified one or more ethnic groups they belonged to, and when selected Māori ethnicity was prioritised above Pasifika, and both above others in its coding. Data were extracted from the prospectively collected cardiothoracic surgical unit database. Critical pre-operative state was defined as having inotropic support, cardiogenic shock, mechanical ventilation and/or cardiopulmonary resuscitation. Malperfusion syndrome were defined as the presence of coronary, limb, brain and/or abdominal viscera ischaemia of new onset related to the aortic dissection, using clinical, biomarker and radiological tests. Creatinine clearance was calculated using the Cockcroft-Gault formula. The EuroSCORE and EuroSCORE II were retrospectively calculated.7,8 The Society of Thoracic Surgeon’s (STS) definitions was used for all outcomes including operative mortality (in-hospital or within 30 days) and post-operative complications.9 Total mortality during follow-up from operation date until 31 January 2019 was checked against the National Mortality Database, and late mortality defined by all deaths that occurred after the operative mortality defined period.
Quantitative and categorical variables were described using mean+/-standard deviation and frequency (percentage) respectively. Univariable analysis was performed using Analysis of Variance (ANOVA) and Chi-squared tests respectively. Survival was presented using Kaplan-Meier plots and compared by the log-rank test. Age-standardisation to calculate standardised mortality ratio (SMR) for operative and late mortality for Māori and Pasifika patients compared to other ethnicities was performed using the 2013 New Zealand Census District Health Board and ethnic group-based population age structures. Stepwise logistic regression and Cox Proportional Hazards regression were the multivariable analysis techniques used for cross-sectional and longitudinal outcomes. The significance level was set at P-value less than 0.05 and all tests were two-tailed.
Results
Among 327 aortic dissection surgery patients, the ethnic breakdown was Māori 45 (14%), Pasifika 91 (28%) and other 191 (58%). Table 1 lists the characteristics of the cohort. Māori and Pasifika patients were significantly younger, had higher body mass index and higher prevalence of hypertension, but lower EuroSCORE, EuroSCORE II and presentation with critical pre-operative state than other patients. Māori patients also had a higher prevalence of smoking and family history of aortic dissection than other patients.
Table 1: Cohort characteristics and outcomes.
Operative variables and outcomes are shown in Table 2. There was no statistically significant difference in operative mortality by ethnicity (11–22%), or post-operative complications (composite 62–70%). Figure 1 shows the survival curves by ethnicity with a mean follow-up of 4.3+/-3.3 years, where 1, 5 and 10-year survival were 86, 74 and 54% for Māori; 79, 76 and 72% for Pasifika; and 74, 66 and 54% for Other ethnicities (log-rank P=0.185). The SMR (95% confidence intervals) for operative mortality were 1.18 (0.43–2.62) for Māori and 6.00 (3.67–9.30) for Pasifika; and for late mortality 5.71 (2.90–10.2) and 1.95 (0.72–4.33) respectively.
Table 2: Operative variables and outcomes.
Figure 1: Kaplan-Meier survival curve of the cohort by ethnicity (log-rank p-value P=0.19).
Multivariable analysis are shown in Table 3. Critical pre-operative state, malperfusion syndrome and cross-clamp time were independent predictors of both operative mortality and composite morbidity, while Māori ethnicity and history of myocardial infarction were independently associated with higher late mortality.
Table 3: Multivariable analysis.
Discussion
Unlike other types of cardiovascular disease, few studies have assessed the relationship between type A aortic dissection and ethnicity,10,11 including one other study from New Zealand.12 Pasifika ethnicity is over-represented at 28% in our cohort compared to just 7% in the New Zealand 2018 Census ethnicity breakdown, and non-Māori or Pasifika ethnicities were under-represented (58% versus 80%).13 Māori was previously reported to have significantly higher prevalence of aortic dissection than non-Māori,12 though in our study it was the same as the 14% from the latest Census.12 Non-white and African-American ethnic groups have also been found to have higher prevalence of aortic dissection than their counterparts.10,11 Reviewing the clinical characteristics of aortic dissection patients may provide insight into the ethnic discrepancies of this condition.
Māori and Pasifika patients were significantly younger, which may highlight both their underlying susceptibility for aortic dissection and worse control of cardiovascular risk factors. They had a higher prevalence of hypertension and smoking, both of which are associated with aortic pathologies.3,4,12 Māori in particular had family history of aortic dissection in 11%, more so than other ethnicities as a known risk factor for dissection. These findings are consistent with studies of aortic dissection,10,11 and other cardiovascular diseases, and targeting them for prevention is critical for this condition.1,2 Partly because they are younger, Māori and Pasifika patients appear to tolerate aortic dissection better with lower proportion presenting in critical pre-operative state. In a previous study of coronary artery bypass grafting surgery, characteristics and outcomes from our institution also found Māori to be younger, with higher body mass index, prevalence of diabetes, smoking, heart failure and dialysis, suggesting similarly a greater burden of cardiovascular disease at younger age.14
There were no differences in all in-hospital surgical outcomes by ethnicity, similarly observed in other studies.10,11 Their risk profiles need to be taken into context, however, with Māori and Pasifika patients being younger and having lower proportion with critical pre-operative state, both established adverse prognosticators in cardiac surgery, and lower EuroSCOREs.7–9 After age-standardisation, Pasifika patients had markedly higher operative mortality than other ethnic groups. Although Māori patients did not display this, they were also associated with higher operative and medium-term mortality as well as composite morbidity in a previous local study for coronary artery bypass grafting surgery.14 Greater attention needs to be directed to the peri-operative management of both ethnicities recommended by guidelines such as replacing the aortic valve, root and repairing supra-aortic branches, descending aorta and other visceral vessels if the dissection involve or compromises those areas, and blood pressure control.4 Female sex was previously found to have a strong association with operative mortality of aortic dissection for all New Zealand ethnicities,12 but this was not found in our study.
After aortic dissection surgeries, most deaths and complications occur during the index hospitalisation, but once patients get through this early phase, long-term prognosis is generally favourable.3–5 It is concerning nevertheless that Māori patients had higher age-standardised late mortality, and remained independently associated with higher late mortality in multivariable analysis, and this trend had also previously been seen.12 Their higher prevalence of family history of aortic dissection, and numerically but not statistically more patients with bicuspid aortic valve may contribute to further aortic events. Control of risk factors like hypertension and clinical and close imaging surveillance are the key guideline recommendations long-term after aortic dissection, and the worse outcomes for Māori may be related to impaired implementation.4,15 Strategies including education, strict risk factor control and attendance to follow-up are critical for these patients with the potential to improve their outcomes. For imaging surveillance after aortic dissection surgery, the European Society of Cardiology guidelines recommend aortic imaging at 1 month, 6 month, 12 months, and if stable then this can be spaced out but remain regular.4 Computed tomography (CT) is preferred with magnetic resonance imaging (MRI) as an alternative. The joint guidelines of American Society of Echocardiography and European Society of Cardiovascular imaging recommend aortic imaging at 1, 3, 6 and 12 months followed by yearly examination, again with either CT or MRI.15
This study had some limitations. It is a single-centre observational study. The study had modest power with regards to limited numbers of particularly Māori and Pasifika patients. We did not investigate non-type A aortic dissection or those managed conservatively with medical therapy and/or endovascular treatments. The aetiology of dissection wasn’t routinely investigated so the presence of associated conditions such as Marfan syndrome are unknown. Other characteristics we didn’t collect include time from presentation to surgery, frailty, blood pressure control and medications, cause of death, peri-operative myocardial infarction, cardiovascular readmissions and recurrence of dissection and/or repeat operation. We also were unable to perform age-standardisation analysis, which may have better presented any differences in outcomes by ethnicity given baseline differences in age.
In conclusion, Pasifika patients were over-represented, Māori patients similarly represented and non-Māori or non-Pasifika ethnicities under-represented in our aortic dissection surgery cohort compared to the general population. Māori and Pasifika patients were significantly younger and presented less unwell, but had higher prevalence of cardiovascular risk factors. Importantly, Pasifika and Māori patients had significantly higher age-standardised operative and late mortality respectively. Education, strict risk factor control and surveillance are critical in primary and secondary prevention of aortic dissection, especially ethnicities at high risk.
Summary
Abstract
Aortic dissection is a life-threatening condition frequently requiring emergency surgery. Key risk factors include hypertension and aortopathy syndromes; however, possible ethnic associations and differences in presentation and outcomes are less well established. We compared characteristics and outcomes of type A aortic dissection surgery by ethnicity.
Aim
Method
Consecutive patients having type A aortic dissection surgery at Auckland City Hospital March 2003–March 2017 were divided into three ethnic groups: Māori, Pasifika and ‘other’, and analysed for characteristics, presentation and outcomes.
Results
Among 327 patients, 45 (14%) were Māori, 91 (28%) were Pasifika Islander and 191 (58%) were other ethnicities. Mean age was lowest for Māori 51+/-12 years, then Pasifika 56+/-12 and other ethnicities 63+/-13 (P<0.001). Māori and Pasifika ethnicities had higher body mass index, more hypertension, dyslipidaemia and smoking, but lower proportion presenting in critical pre-operative state. Operative mortality occurred in 5 (11%), 18 (20%) and 42 (22%) for Māori, Pasifika and other ethnicities (P=0.258). Pasifika had higher age-standardised operative mortality standardised mortality ratio 6.00, 95% confidence interval 3.67–9.30 than ‘other’ ethnicities, while Māori had higher age-standardised late mortality 5.71, 2.90–10.2 respectively, and the latter association persisted in multivariable analysis. Critical pre-operative state and malperfusion syndrome independently predicted operative mortality.
Conclusion
Māori and Pasifika patients were younger and present less unwell with type A aortic dissection, but had higher prevalence of cardiovascular risk factors. They had higher age-standardised late and operative mortality respectively, suggesting that aggressive management and risk factor control are critical for these patients.
Author Information
Acknowledgements
Correspondence
Correspondence Email
Competing Interests
1. Disney G, Teng A, Atkinson J, Wilson N, Blakely T. Changing ethnic inequalities in mortality in New Zealand over 30 years: linked cohort studies with 68.9 million person-years of follow-up. Popul Health Metr 2017; 15:15.
2. Grey C, Jackson R, Wells S, Wu B, Poppe K, Harwood M, Sundborn G, Kerr AJ. Trends in ischaemic heart disease: patterns of hospitalisation and mortality rates differ by ethnicity (ANZACS-QI 21). N Z Med J 2018; 131(1478):21–31.
3. Evangelista A, Isselbacher EM, Bossone E, Gleason TG, Eusanio MD, Sechtem U, Ehrlich MP, Trimarchi S, Braverman AC, Myrmel T, Harris KM, Hutchinson S, O'Gara P, Suzuki T, Nienaber CA, Eagle KA; IRAD Investigators. Insights from the International Registry of Acute Aortic Dissection: A 20-Year Experience of Collaborative Clinical Research. Circulation 2018; 137(17):1846–1860.
4. Erbel R, Aboyans V, Boileau C, Bossone E, Bartolomeo RD, Eggebrecht H, Evangelista A, Falk V, Frank H, Gaemperli O, Grabenwöger M, Haverich A, Iung B, Manolis AJ, Meijboom F, Nienaber CA, Roffi M, Rousseau H, Sechtem U, Sirnes PA, Allmen RS, Vrints CJ; ESC Committee for Practice Guidelines. 2014 ESC Guidelines on the diagnosis and treatment of aortic diseases: Document covering acute and chronic aortic diseases of the thoracic and abdominal aorta of the adult. The Task Force for the Diagnosis and Treatment of Aortic Diseases of the European Society of Cardiology (ESC). Eur Heart J. 2014; 35(41):2873–926.
5. Lee TC, Kon Z, Cheema FH, Grau-Sepulveda MV, Englum B, Kim S, Chaudhuri PS, Thourani VH Ailawadi G, Hughes GC, Williams ML, Brennan JM, Svensson L, Gammie JS. Contemporary management and outcomes of acute type A aortic dissection: An analysis of the STS adult cardiac surgery database. J Card Surg 2018; 33(1):7–18.
6. Cockcroft DW, Gault MH. Prediction of Creatinine Clearance from Serum Creatinine. Nephron 1976; 16:31–41.
7. Roques F, Michel P, Goldstone AR, Nashef SA. The logistic EuroSCORE. Eur Heart J. 2003; 24:881–2.
8. Nashef SA, Roques F, Sharples LD, Nilsson J, Smith C, Goldstone AR, Lockowandt U. EuroSCORE II. Eur J Cardiothorac Surg 2012; 41:734–44.
9. O'Brien SM, Feng L, He X, Xian Y, Jacobs JP, Badhwar V, Kurlansky PA, Furnary AP, Cleveland JC Jr, Lobdell KW, Vassileva C, Wyler von Ballmoos MC, Thourani VH, Rankin JS, Edgerton JR, D'Agostino RS, Desai ND, Edwards FH, Shahian DM. The Society of Thoracic Surgeons 2018 Adult Cardiac Surgery Risk Models: Part 2-Statistical Methods and Results. Ann Thorac Surg. 2018; 105(5):1419–1428.
10. Harris D, Klyushnenkova E, Kalsi R, Garrido D, Bhardwaj A, Rabin J, Toursavadkohi S, Diaz J, Crawford R. Non-White Race is an Independent Risk Factor for Hospitalization for Aortic Dissection. Ethn Dis 2016; 26(3):363–8.
11. Bossone E, Pyeritz RE, O'Gara P, Harris KM, Braverman AC, Pape L, Russo MJ, Hughes GC, Tsai TT, Montgomery DG, Nienaber CA, Isselbacher EM, Eagle KA; International Registry of Acute Aortic Dissection (IRAD) Investigators. Acute aortic dissection in blacks: insights from the International Registry of Acute Aortic Dissection. Am J Med 2013; 126(10):909–15.
12. Gupta A, Subramaniam P, Subramaniam P, Hulme K. The sharp end of cardiovascular disease in New Zealand: A review of acute type A aortic dissections of the Waikato. N Z Med J 2015; 128(1419):22–8.
13. Statistics New Zealand [Internet]. Wellington: 2018 Census population and dwelling counts". [Cited 2019 October 4] Available from: http://www.stats.govt.nz/assets/Uploads/2018-Census-population-and-dwelling-counts/Download-data/2018-census-population-and-dwelling-counts.xlsx
14. Wang TK, Ramanathan T, Stewart R, Crengle S, Gamble G, White H. Māori have worse outcomes after coronary artery bypass grafting than Europeans in New Zealand. N Z Med J. 2013; 126(1379):12–22.
15. Goldstein SA, Evangelista A, Abbara S, Arai A, Asch FM, Badano LP, Bolen MA, Connolly HM, Cuéllar-Calàbria H, Czerny M, Devereux RB, Erbel RA, Fattori R, Isselbacher EM, Lindsay JM, McCulloch M, Michelena HI, Nienaber CA, Oh JK, Pepi M, Taylor AJ, Weinsaft JW, Zamorano JL, Dietz H, Eagle K, Elefteriades J, Jondeau G, Rousseau H, Schepens M. J Am Soc Echocardiogr. Multimodality imaging of diseases of the thoracic aorta in adults: from the American Society of Echocardiography and the European Association of Cardiovascular Imaging: endorsed by the Society of Cardiovascular Computed Tomography and Society for Cardiovascular Magnetic Resonance 2015; 28(2):119–82.
Contact diana@nzma.org.nz
for the PDF of this article
Comparison of characteristics and outcomes for type A aortic dissection surgery by Māori, Pasifika or other ethnicities
View Article PDF
Ethnic disparities is a leading problem in healthcare, affecting many cardiovascular conditions and mortality rates in New Zealand.1,2 Type A aortic dissection has high fatality from associated cardiac tamponade, malperfusion of critical organ(s), aortic regurgitation and vessel rupture.3,4 Emergency surgery is generally recommended due to the high risk of death if left untreated, 1–3%/hour in the first 24 hours reaching hospital, 30% at one week and 90% at one month; however, operative mortality remains high at 17–25% in contemporary literature.3,5 Key risk factors include hypertension and aortopathy syndromes; however, possible ethnic associations and differences in presentation and outcomes are less well established.3,4 We reviewed our type A aortic dissection surgery experience by ethnicity.
Methods
Consecutive type A aortic dissection surgeries performed at Auckland City Hospital during March 2003–March 2017 were divided into three ethnic groups—Māori, Pasifika and Other. Ethnicity was obtained from clinical records, whereby patients reported their self-identified one or more ethnic groups they belonged to, and when selected Māori ethnicity was prioritised above Pasifika, and both above others in its coding. Data were extracted from the prospectively collected cardiothoracic surgical unit database. Critical pre-operative state was defined as having inotropic support, cardiogenic shock, mechanical ventilation and/or cardiopulmonary resuscitation. Malperfusion syndrome were defined as the presence of coronary, limb, brain and/or abdominal viscera ischaemia of new onset related to the aortic dissection, using clinical, biomarker and radiological tests. Creatinine clearance was calculated using the Cockcroft-Gault formula. The EuroSCORE and EuroSCORE II were retrospectively calculated.7,8 The Society of Thoracic Surgeon’s (STS) definitions was used for all outcomes including operative mortality (in-hospital or within 30 days) and post-operative complications.9 Total mortality during follow-up from operation date until 31 January 2019 was checked against the National Mortality Database, and late mortality defined by all deaths that occurred after the operative mortality defined period.
Quantitative and categorical variables were described using mean+/-standard deviation and frequency (percentage) respectively. Univariable analysis was performed using Analysis of Variance (ANOVA) and Chi-squared tests respectively. Survival was presented using Kaplan-Meier plots and compared by the log-rank test. Age-standardisation to calculate standardised mortality ratio (SMR) for operative and late mortality for Māori and Pasifika patients compared to other ethnicities was performed using the 2013 New Zealand Census District Health Board and ethnic group-based population age structures. Stepwise logistic regression and Cox Proportional Hazards regression were the multivariable analysis techniques used for cross-sectional and longitudinal outcomes. The significance level was set at P-value less than 0.05 and all tests were two-tailed.
Results
Among 327 aortic dissection surgery patients, the ethnic breakdown was Māori 45 (14%), Pasifika 91 (28%) and other 191 (58%). Table 1 lists the characteristics of the cohort. Māori and Pasifika patients were significantly younger, had higher body mass index and higher prevalence of hypertension, but lower EuroSCORE, EuroSCORE II and presentation with critical pre-operative state than other patients. Māori patients also had a higher prevalence of smoking and family history of aortic dissection than other patients.
Table 1: Cohort characteristics and outcomes.
Operative variables and outcomes are shown in Table 2. There was no statistically significant difference in operative mortality by ethnicity (11–22%), or post-operative complications (composite 62–70%). Figure 1 shows the survival curves by ethnicity with a mean follow-up of 4.3+/-3.3 years, where 1, 5 and 10-year survival were 86, 74 and 54% for Māori; 79, 76 and 72% for Pasifika; and 74, 66 and 54% for Other ethnicities (log-rank P=0.185). The SMR (95% confidence intervals) for operative mortality were 1.18 (0.43–2.62) for Māori and 6.00 (3.67–9.30) for Pasifika; and for late mortality 5.71 (2.90–10.2) and 1.95 (0.72–4.33) respectively.
Table 2: Operative variables and outcomes.
Figure 1: Kaplan-Meier survival curve of the cohort by ethnicity (log-rank p-value P=0.19).
Multivariable analysis are shown in Table 3. Critical pre-operative state, malperfusion syndrome and cross-clamp time were independent predictors of both operative mortality and composite morbidity, while Māori ethnicity and history of myocardial infarction were independently associated with higher late mortality.
Table 3: Multivariable analysis.
Discussion
Unlike other types of cardiovascular disease, few studies have assessed the relationship between type A aortic dissection and ethnicity,10,11 including one other study from New Zealand.12 Pasifika ethnicity is over-represented at 28% in our cohort compared to just 7% in the New Zealand 2018 Census ethnicity breakdown, and non-Māori or Pasifika ethnicities were under-represented (58% versus 80%).13 Māori was previously reported to have significantly higher prevalence of aortic dissection than non-Māori,12 though in our study it was the same as the 14% from the latest Census.12 Non-white and African-American ethnic groups have also been found to have higher prevalence of aortic dissection than their counterparts.10,11 Reviewing the clinical characteristics of aortic dissection patients may provide insight into the ethnic discrepancies of this condition.
Māori and Pasifika patients were significantly younger, which may highlight both their underlying susceptibility for aortic dissection and worse control of cardiovascular risk factors. They had a higher prevalence of hypertension and smoking, both of which are associated with aortic pathologies.3,4,12 Māori in particular had family history of aortic dissection in 11%, more so than other ethnicities as a known risk factor for dissection. These findings are consistent with studies of aortic dissection,10,11 and other cardiovascular diseases, and targeting them for prevention is critical for this condition.1,2 Partly because they are younger, Māori and Pasifika patients appear to tolerate aortic dissection better with lower proportion presenting in critical pre-operative state. In a previous study of coronary artery bypass grafting surgery, characteristics and outcomes from our institution also found Māori to be younger, with higher body mass index, prevalence of diabetes, smoking, heart failure and dialysis, suggesting similarly a greater burden of cardiovascular disease at younger age.14
There were no differences in all in-hospital surgical outcomes by ethnicity, similarly observed in other studies.10,11 Their risk profiles need to be taken into context, however, with Māori and Pasifika patients being younger and having lower proportion with critical pre-operative state, both established adverse prognosticators in cardiac surgery, and lower EuroSCOREs.7–9 After age-standardisation, Pasifika patients had markedly higher operative mortality than other ethnic groups. Although Māori patients did not display this, they were also associated with higher operative and medium-term mortality as well as composite morbidity in a previous local study for coronary artery bypass grafting surgery.14 Greater attention needs to be directed to the peri-operative management of both ethnicities recommended by guidelines such as replacing the aortic valve, root and repairing supra-aortic branches, descending aorta and other visceral vessels if the dissection involve or compromises those areas, and blood pressure control.4 Female sex was previously found to have a strong association with operative mortality of aortic dissection for all New Zealand ethnicities,12 but this was not found in our study.
After aortic dissection surgeries, most deaths and complications occur during the index hospitalisation, but once patients get through this early phase, long-term prognosis is generally favourable.3–5 It is concerning nevertheless that Māori patients had higher age-standardised late mortality, and remained independently associated with higher late mortality in multivariable analysis, and this trend had also previously been seen.12 Their higher prevalence of family history of aortic dissection, and numerically but not statistically more patients with bicuspid aortic valve may contribute to further aortic events. Control of risk factors like hypertension and clinical and close imaging surveillance are the key guideline recommendations long-term after aortic dissection, and the worse outcomes for Māori may be related to impaired implementation.4,15 Strategies including education, strict risk factor control and attendance to follow-up are critical for these patients with the potential to improve their outcomes. For imaging surveillance after aortic dissection surgery, the European Society of Cardiology guidelines recommend aortic imaging at 1 month, 6 month, 12 months, and if stable then this can be spaced out but remain regular.4 Computed tomography (CT) is preferred with magnetic resonance imaging (MRI) as an alternative. The joint guidelines of American Society of Echocardiography and European Society of Cardiovascular imaging recommend aortic imaging at 1, 3, 6 and 12 months followed by yearly examination, again with either CT or MRI.15
This study had some limitations. It is a single-centre observational study. The study had modest power with regards to limited numbers of particularly Māori and Pasifika patients. We did not investigate non-type A aortic dissection or those managed conservatively with medical therapy and/or endovascular treatments. The aetiology of dissection wasn’t routinely investigated so the presence of associated conditions such as Marfan syndrome are unknown. Other characteristics we didn’t collect include time from presentation to surgery, frailty, blood pressure control and medications, cause of death, peri-operative myocardial infarction, cardiovascular readmissions and recurrence of dissection and/or repeat operation. We also were unable to perform age-standardisation analysis, which may have better presented any differences in outcomes by ethnicity given baseline differences in age.
In conclusion, Pasifika patients were over-represented, Māori patients similarly represented and non-Māori or non-Pasifika ethnicities under-represented in our aortic dissection surgery cohort compared to the general population. Māori and Pasifika patients were significantly younger and presented less unwell, but had higher prevalence of cardiovascular risk factors. Importantly, Pasifika and Māori patients had significantly higher age-standardised operative and late mortality respectively. Education, strict risk factor control and surveillance are critical in primary and secondary prevention of aortic dissection, especially ethnicities at high risk.
Summary
Abstract
Aortic dissection is a life-threatening condition frequently requiring emergency surgery. Key risk factors include hypertension and aortopathy syndromes; however, possible ethnic associations and differences in presentation and outcomes are less well established. We compared characteristics and outcomes of type A aortic dissection surgery by ethnicity.
Aim
Method
Consecutive patients having type A aortic dissection surgery at Auckland City Hospital March 2003–March 2017 were divided into three ethnic groups: Māori, Pasifika and ‘other’, and analysed for characteristics, presentation and outcomes.
Results
Among 327 patients, 45 (14%) were Māori, 91 (28%) were Pasifika Islander and 191 (58%) were other ethnicities. Mean age was lowest for Māori 51+/-12 years, then Pasifika 56+/-12 and other ethnicities 63+/-13 (P<0.001). Māori and Pasifika ethnicities had higher body mass index, more hypertension, dyslipidaemia and smoking, but lower proportion presenting in critical pre-operative state. Operative mortality occurred in 5 (11%), 18 (20%) and 42 (22%) for Māori, Pasifika and other ethnicities (P=0.258). Pasifika had higher age-standardised operative mortality standardised mortality ratio 6.00, 95% confidence interval 3.67–9.30 than ‘other’ ethnicities, while Māori had higher age-standardised late mortality 5.71, 2.90–10.2 respectively, and the latter association persisted in multivariable analysis. Critical pre-operative state and malperfusion syndrome independently predicted operative mortality.
Conclusion
Māori and Pasifika patients were younger and present less unwell with type A aortic dissection, but had higher prevalence of cardiovascular risk factors. They had higher age-standardised late and operative mortality respectively, suggesting that aggressive management and risk factor control are critical for these patients.
Author Information
Acknowledgements
Correspondence
Correspondence Email
Competing Interests
1. Disney G, Teng A, Atkinson J, Wilson N, Blakely T. Changing ethnic inequalities in mortality in New Zealand over 30 years: linked cohort studies with 68.9 million person-years of follow-up. Popul Health Metr 2017; 15:15.
2. Grey C, Jackson R, Wells S, Wu B, Poppe K, Harwood M, Sundborn G, Kerr AJ. Trends in ischaemic heart disease: patterns of hospitalisation and mortality rates differ by ethnicity (ANZACS-QI 21). N Z Med J 2018; 131(1478):21–31.
3. Evangelista A, Isselbacher EM, Bossone E, Gleason TG, Eusanio MD, Sechtem U, Ehrlich MP, Trimarchi S, Braverman AC, Myrmel T, Harris KM, Hutchinson S, O'Gara P, Suzuki T, Nienaber CA, Eagle KA; IRAD Investigators. Insights from the International Registry of Acute Aortic Dissection: A 20-Year Experience of Collaborative Clinical Research. Circulation 2018; 137(17):1846–1860.
4. Erbel R, Aboyans V, Boileau C, Bossone E, Bartolomeo RD, Eggebrecht H, Evangelista A, Falk V, Frank H, Gaemperli O, Grabenwöger M, Haverich A, Iung B, Manolis AJ, Meijboom F, Nienaber CA, Roffi M, Rousseau H, Sechtem U, Sirnes PA, Allmen RS, Vrints CJ; ESC Committee for Practice Guidelines. 2014 ESC Guidelines on the diagnosis and treatment of aortic diseases: Document covering acute and chronic aortic diseases of the thoracic and abdominal aorta of the adult. The Task Force for the Diagnosis and Treatment of Aortic Diseases of the European Society of Cardiology (ESC). Eur Heart J. 2014; 35(41):2873–926.
5. Lee TC, Kon Z, Cheema FH, Grau-Sepulveda MV, Englum B, Kim S, Chaudhuri PS, Thourani VH Ailawadi G, Hughes GC, Williams ML, Brennan JM, Svensson L, Gammie JS. Contemporary management and outcomes of acute type A aortic dissection: An analysis of the STS adult cardiac surgery database. J Card Surg 2018; 33(1):7–18.
6. Cockcroft DW, Gault MH. Prediction of Creatinine Clearance from Serum Creatinine. Nephron 1976; 16:31–41.
7. Roques F, Michel P, Goldstone AR, Nashef SA. The logistic EuroSCORE. Eur Heart J. 2003; 24:881–2.
8. Nashef SA, Roques F, Sharples LD, Nilsson J, Smith C, Goldstone AR, Lockowandt U. EuroSCORE II. Eur J Cardiothorac Surg 2012; 41:734–44.
9. O'Brien SM, Feng L, He X, Xian Y, Jacobs JP, Badhwar V, Kurlansky PA, Furnary AP, Cleveland JC Jr, Lobdell KW, Vassileva C, Wyler von Ballmoos MC, Thourani VH, Rankin JS, Edgerton JR, D'Agostino RS, Desai ND, Edwards FH, Shahian DM. The Society of Thoracic Surgeons 2018 Adult Cardiac Surgery Risk Models: Part 2-Statistical Methods and Results. Ann Thorac Surg. 2018; 105(5):1419–1428.
10. Harris D, Klyushnenkova E, Kalsi R, Garrido D, Bhardwaj A, Rabin J, Toursavadkohi S, Diaz J, Crawford R. Non-White Race is an Independent Risk Factor for Hospitalization for Aortic Dissection. Ethn Dis 2016; 26(3):363–8.
11. Bossone E, Pyeritz RE, O'Gara P, Harris KM, Braverman AC, Pape L, Russo MJ, Hughes GC, Tsai TT, Montgomery DG, Nienaber CA, Isselbacher EM, Eagle KA; International Registry of Acute Aortic Dissection (IRAD) Investigators. Acute aortic dissection in blacks: insights from the International Registry of Acute Aortic Dissection. Am J Med 2013; 126(10):909–15.
12. Gupta A, Subramaniam P, Subramaniam P, Hulme K. The sharp end of cardiovascular disease in New Zealand: A review of acute type A aortic dissections of the Waikato. N Z Med J 2015; 128(1419):22–8.
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Comparison of characteristics and outcomes for type A aortic dissection surgery by Māori, Pasifika or other ethnicities
Ethnic disparities is a leading problem in healthcare, affecting many cardiovascular conditions and mortality rates in New Zealand.
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